Phobos: Doomed Moon of Mars

Explanation: This moon is doomed. Mars , the red planet named for the Roman god of war , has two tiny moons, Phobos and Deimos , whose names are derived from the Greek for Fear and Panic . These martian moons may well be captured asteroids originating in the main asteroid belt between Mars and Jupiter or perhaps from even more distant reaches of our Solar System . The larger moon, Phobos , is indeed seen to be a cratered, asteroid-like object in this stunning color image from the robotic Mars Reconnaissance Orbiter , with objects as small as 10 meters visible. But Phobos orbits so close to Mars - about 5,800 kilometers above the surface compared to 400,000 kilometers for our Moon - that gravitational tidal forces are dragging it down. In perhaps 50 million years, Phobos is expected to disintegrate into a ring of debris.